They actually did this as long as I can remember.
It causes issues when you need the resources elsewhere (like iron for concrete),
or if you have loops that you are trying to solve with the matrix solver, like burner drills on coal burning coal for power...

if i understood the problem, it is to manage productivity
sample: https://imgur.com/a/Z3vqrt0
but if I can have an example of a problematic case, I can search to resolve

Then you need separate "signals" for "ore as an item" and "unextracted ore in the ground" ?
I just gave you an example ?
Here's a screenshot anyway :
https://i.imgur.com/sXGXYQc.jpg
(If the matrix solver was able to work properly in this case, the input would show 0 input coal...

you think of thing like this https://imgur.com/a/mR01yM0
it is to confirm that I understood your request

Yeah, pretty much - though some people might indeed still want to know how much ore was actually removed from the ground ?